Assertion (A): | A photon has no rest mass, yet it carries definite momentum. |
Reason (R): | Momentum of a photon is due to its energy and hence its equivalent mass. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | Both (A) and (R) are False. |
Assertion (A): | The threshold frequency of the photoelectric effect supports the particle nature of sunlight. |
Reason (R): | If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Assertion (A): | Mass of a moving photon varies inversely to the wavelength. |
Reason (R): | \(\times\)(speed of light)2. | Energy of the particle = Mass
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | (A) is false but (R) is true. |
When ultraviolet rays strike a metal plate, the photoelectric effect does not occur. It occurs by the incidence of:
1. Infrared rays
2. X-rays
3. Radio wave
4. Lightwave
If the K.E. of an electron and a photon is the same, then the relation between their de-Broglie wavelength will be:
1.
2.
3.
4.
A photosensitive metallic surface has a work function of hν0. If photons of energy 2hν0 fall on this surface, the electrons come out with a maximum velocity of 4 × 106 m/s. When the photon energy is increased to 5hν0, then the maximum velocity of photoelectrons will be:
1. 2 ×107 m/s
2. 2 × 106 m/s
3. 8 × 105 m/s
4. 8 × 106 m/s
The work function of a metal surface is φ = 1.5 eV. If a light of wavelength 5000 Å falls on it, then the maximum K.E. of the ejected electron will be:
1. | 1.2 eV | 2. | 0.98 eV |
3. | 0.45 eV | 4. | 0 eV |
The work functions for metals A, B, and C are respectively 1.92 eV, 2.0 eV, and 5 eV. According to Einstein's equation, the metals that will emit photoelectrons for a radiation of wavelength 4100 Å is/are:
1. None
2. A only
3. A and B only
4. All the three metals
A light of wavelength \(\lambda \) is incident on the metal surface and the ejected fastest electron has speed \(v.\) If the wavelength is changed to \(\frac{3\lambda}{4},\) then the speed of the fastest emitted electron will be:
1. | \(\sqrt{\frac{4}{3}}v\) | smaller than
2. | \(\sqrt{\frac{4}{3}}\)\(v\) | greater than
3. | \(2v\) |
4. | zero |
What did Einstein prove by the photo-electric effect?
1. E = h\(\nu\)
2.
3.
4.